Salt Lake City, Utah (CNN) -- By all accounts, Michael Burdell was a gentle soul with a soft spot for people in need.

A Vietnam veteran, he was issued a weapon but refused to carry it, serving as a technician on communications equipment, his fiancée, Donna Nu, said in court documents.

The two had known each other for six years. Had Burdell, a 36-year-old attorney, not died on April 2, 1985, shot to death by Ronnie Lee Gardner during Gardner's escape attempt at a Salt Lake City courthouse, they would have been married.

But Nu, along with Burdell's friend, Ron Temu, and his 86-year-old father, Joseph Burdell, are now arguing on Gardner's behalf.

Gardner is to face a Utah firing squad on June 18. But driven by Burdell's pacifism and opposition to the death penalty, the three have filed statements in the case seeking to have his sentence commuted.

"Michael Burdell would not have wanted Ronnie Lee Gardner put to death," Nu said in court documents. "There is absolutely no question about this in my mind."

Legal maneuvers aimed at delaying or avoiding Gardner's execution have accelerated. His defense attorneys went before the Utah Supreme Court this week to argue that he should receive a new sentencing hearing, appealing an earlier state court's denial. The justices took the case under advisement.

On Wednesday, U.S. District Judge Tena Campbell denied a defense request to stop Thursday's commutation hearing before the state Board of Pardons and Parole.

Defense attorney Andrew Parnes had asked Campbell to issue a temporary restraining order, saying he was concerned the hearing would not be fair and impartial because representatives from the Utah attorney general's office were both presenting the state's case at the hearing and advising the board. Attorneys representing the state agency said safeguards were in place to prevent a conflict of interest.

Parnes also said he was concerned the board would not allow some videotaped testimony to be played at the hearing, although the board said it would take the testimony under consideration. He has filed a federal complaint over the matter, which he said was not necessarily nullified by Campbell's decision to let the hearing go forward.

Nu will be among those testifying on Gardner's behalf. The elder Burdell, who lives in North Carolina, said in his statement he would be there as well, if his age did not preclude his traveling to Utah.

Attempts by CNN to speak with Nu on Wednesday were unsuccessful, because she was traveling to Salt Lake City from her Arizona home. Temu did not immediately return a call seeking comment.

The two are members of a Salt Lake City-based religious movement called Summum. Burdell was also a member. Summum was founded in 1975 by the late Corky Ra, also known as Summum Bonum Amon Ra, after he said he was visited by other beings.

Nu said in her statement she met Burdell while the two were living in Arizona and she was making frequent trips to the Summum center in Utah. She introduced Burdell to the movement, and he became a member. They moved to Salt Lake City in 1982.

"In addition to Michael's personal beliefs, the Summum faith opposes capital punishment," Nu said in court documents. "People who take the vows of Summum must pledge never to take the life of another person. Michael Burdell freely took this pledge."

Temu said in his statement he believes Burdell must have been "the poorest attorney on Earth, because he so often represented people who could not afford to pay him." Burdell lived "like a monk," he said, and had few possessions.

On April 2, 1985, Burdell was at the courthouse on a case, representing a fellow Vietnam veteran at no cost. Gardner was also at the courthouse that day, scheduled for a pretrial hearing in the 1984 slaying of Melvyn Otterstrom. He killed Otterstrom after escaping from prison; now, he was planning to escape from custody again.

According to court documents filed by Gardner's defense, he had planned to use a gun that would be left hanging from a water fountain in the basement of the courthouse.

However, an accomplice in the basement handed Gardner a .22-caliber gun instead as he was being led in by guards. Gardner was handcuffed, and his legs chained together. His arms also were fastened to a waist chain that limited how far he could raise his hands.

As soon as Gardner was given the gun, court documents said, he was shot and seriously injured by one of the guards with him. But he managed to "shuffle" into a basement office area, where courthouse archives were kept.

Burdell and another attorney were in the office; they saw Gardner with a gun and hid behind the door as he came inside. As Gardner spotted them and pointed the gun at them, the other attorney fled, leaving Burdell behind.

The other attorney reported hearing Burdell say, "Oh, my God," and Gardner swear before the gun went off, shooting Burdell through the eye. Gardner then grabbed a corrections officer and tried to force him to accompany him out of the building, according to court documents. He also shot bailiff Nick Kirk as he was trying to leave.

Gardner eventually surrendered to authorities on the courthouse lawn. He pleaded guilty in June 1985 to killing Otterstrom and was sentenced to life in prison, with a judge's recommendation that he not be released.

Later that same year, he was convicted of capital murder in Burdell's death. Burdell's father said in court documents filed this year that he does not believe his son's shooting was premeditated.

"Gardner himself had been shot and his shooting my son was a spur-of-the-moment reaction," Joseph Burdell said. "Furthermore," he added, "I do not believe Gardner is the same person today that he was in 1985."

But Otterstrom's friends and family said they support Gardner's execution. Cousin Craig Watson told The Salt Lake Tribune this month, "It's about time justice is served."

Kirk's widow also told the newspaper she supports the death penalty for Gardner, saying the shooting left her husband in constant pain. He was never the same, she said, and died of a heart attack in 1995.

But those who loved Burdell recall his pacifist nature and his desire to help his fellow man. They believe that if Burdell were still alive, he would be campaigning against Gardner's death.

"My son was a caring and generous person who tried to help others," Joseph Burdell said. "It would not have been in his nature to condone Gardner's execution. He would not have approved of it at all."